Narrow web materials can be level wound. By oscillating the narrow web material backwards and forwards across the roll during winding the level winding process provides a stable roll. However traversing the material in this way during winding subjects the web to a camber. Some materials are permanently deformed when subjected to a camber, and for these materials it is preferable to select a winding pattern with, principally, straight, in-line, winding.
An index wind, or step wind, is an arrangement of stacked lanes. The narrow web material is wound in-line for a predetermined number of layers, and then the web traverses over to the next lane position. The web is only subjected to camber during the period of winding when the web traverses from one lane to the next. The degree of camber is determined by the transverse width over which the web needs to be moved, the number of turns through which the traverse is spread, and the actual diameter. To keep the camber to a minimum, an S-shaped velocity profile of the traverse move may be employed.
It is desirable to provide an alternative winding system which would avoid subjecting the narrow web to a camber.